[PATCH] Kprobes/IA64: arch specific handling

This is an IA64 arch specific handling of Kprobes

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ia64/Kconfig.debug

@@ -2,6 +2,17 @@ menu "Kernel hacking"
 
 source "lib/Kconfig.debug"
 
+config KPROBES
+        bool "Kprobes"
+        depends on DEBUG_KERNEL
+        help
+          Kprobes allows you to trap at almost any kernel address and
+          execute a callback function.  register_kprobe() establishes
+          a probepoint and specifies the callback.  Kprobes is useful
+          for kernel debugging, non-intrusive instrumentation and testing.
+          If in doubt, say "N".
+
+
 choice
 	prompt "Physical memory granularity"
 	default IA64_GRANULE_64MB

arch/ia64/kernel/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_SMP)		+= smp.o smpboot.o domain.o
 obj-$(CONFIG_PERFMON)		+= perfmon_default_smpl.o
 obj-$(CONFIG_IA64_CYCLONE)	+= cyclone.o
 obj-$(CONFIG_IA64_MCA_RECOVERY)	+= mca_recovery.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR)	+= uncached.o
 mca_recovery-y			+= mca_drv.o mca_drv_asm.o
 

arch/ia64/kernel/kprobes.c

@@ -0,0 +1,332 @@
+/*
+ *  Kernel Probes (KProbes)
+ *  arch/ia64/kernel/kprobes.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright (C) Intel Corporation, 2005
+ *
+ * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
+ *              <anil.s.keshavamurthy@intel.com> adapted from i386
+ */
+
+#include <linux/config.h>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/preempt.h>
+#include <linux/moduleloader.h>
+
+#include <asm/pgtable.h>
+#include <asm/kdebug.h>
+
+/* kprobe_status settings */
+#define KPROBE_HIT_ACTIVE	0x00000001
+#define KPROBE_HIT_SS		0x00000002
+
+static struct kprobe *current_kprobe;
+static unsigned long kprobe_status;
+
+enum instruction_type {A, I, M, F, B, L, X, u};
+static enum instruction_type bundle_encoding[32][3] = {
+  { M, I, I },				/* 00 */
+  { M, I, I },				/* 01 */
+  { M, I, I },				/* 02 */
+  { M, I, I },				/* 03 */
+  { M, L, X },				/* 04 */
+  { M, L, X },				/* 05 */
+  { u, u, u },  			/* 06 */
+  { u, u, u },  			/* 07 */
+  { M, M, I },				/* 08 */
+  { M, M, I },				/* 09 */
+  { M, M, I },				/* 0A */
+  { M, M, I },				/* 0B */
+  { M, F, I },				/* 0C */
+  { M, F, I },				/* 0D */
+  { M, M, F },				/* 0E */
+  { M, M, F },				/* 0F */
+  { M, I, B },				/* 10 */
+  { M, I, B },				/* 11 */
+  { M, B, B },				/* 12 */
+  { M, B, B },				/* 13 */
+  { u, u, u },  			/* 14 */
+  { u, u, u },  			/* 15 */
+  { B, B, B },				/* 16 */
+  { B, B, B },				/* 17 */
+  { M, M, B },				/* 18 */
+  { M, M, B },				/* 19 */
+  { u, u, u },  			/* 1A */
+  { u, u, u },  			/* 1B */
+  { M, F, B },				/* 1C */
+  { M, F, B },				/* 1D */
+  { u, u, u },  			/* 1E */
+  { u, u, u },  			/* 1F */
+};
+
+int arch_prepare_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long) p->addr;
+	unsigned long bundle_addr = addr & ~0xFULL;
+	unsigned long slot = addr & 0xf;
+	bundle_t bundle;
+	unsigned long template;
+
+	/*
+	 * TODO: Verify that a probe is not being inserted
+	 *       in sensitive regions of code
+	 * TODO: Verify that the memory holding the probe is rwx
+	 * TODO: verify this is a kernel address
+	 */
+	memcpy(&bundle, (unsigned long *)bundle_addr, sizeof(bundle_t));
+	template = bundle.quad0.template;
+	if (((bundle_encoding[template][1] == L) && slot > 1) || (slot > 2)) {
+		printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n", addr);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+void arch_copy_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+	unsigned long bundle_addr = addr & ~0xFULL;
+
+	memcpy(&p->ainsn.insn.bundle, (unsigned long *)bundle_addr,
+				sizeof(bundle_t));
+	memcpy(&p->opcode.bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
+}
+
+void arch_arm_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+	unsigned long arm_addr = addr & ~0xFULL;
+	unsigned long slot = addr & 0xf;
+	unsigned long template;
+	bundle_t bundle;
+
+	memcpy(&bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
+
+	template = bundle.quad0.template;
+	if (slot == 1 && bundle_encoding[template][1] == L)
+		slot = 2;
+	switch (slot) {
+	case 0:
+		bundle.quad0.slot0 = BREAK_INST;
+		break;
+	case 1:
+		bundle.quad0.slot1_p0 = BREAK_INST;
+		bundle.quad1.slot1_p1 = (BREAK_INST >> (64-46));
+		break;
+	case 2:
+		bundle.quad1.slot2 = BREAK_INST;
+		break;
+	}
+
+ 	/* Flush icache for the instruction at the emulated address */
+	flush_icache_range((unsigned long)&p->ainsn.insn.bundle,
+			(unsigned long)&p->ainsn.insn.bundle +
+			sizeof(bundle_t));
+	/*
+	 * Patch the original instruction with the probe instruction
+	 * and flush the instruction cache
+	 */
+	memcpy((char *) arm_addr, (char *) &bundle, sizeof(bundle_t));
+	flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
+}
+
+void arch_disarm_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+	unsigned long arm_addr = addr & ~0xFULL;
+
+	/* p->opcode contains the original unaltered bundle */
+	memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
+	flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+}
+
+/*
+ * We are resuming execution after a single step fault, so the pt_regs
+ * structure reflects the register state after we executed the instruction
+ * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
+ * the ip to point back to the original stack address, and if we see that
+ * the slot has incremented back to zero, then we need to point to the next
+ * slot location.
+ */
+static void resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long bundle = (unsigned long)p->addr & ~0xFULL;
+
+	/*
+	 * TODO: Handle cases where kprobe was inserted on a branch instruction
+	 */
+
+	if (!ia64_psr(regs)->ri)
+		regs->cr_iip = bundle + 0x10;
+	else
+		regs->cr_iip = bundle;
+
+	ia64_psr(regs)->ss = 0;
+}
+
+static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long bundle_addr = (unsigned long) &p->ainsn.insn.bundle;
+	unsigned long slot = (unsigned long)p->addr & 0xf;
+
+	/* Update instruction pointer (IIP) and slot number (IPSR.ri) */
+	regs->cr_iip = bundle_addr & ~0xFULL;
+
+	if (slot > 2)
+		slot = 0;
+
+	ia64_psr(regs)->ri = slot;
+
+	/* turn on single stepping */
+	ia64_psr(regs)->ss = 1;
+}
+
+static int pre_kprobes_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	int ret = 0;
+	kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
+
+	preempt_disable();
+
+	/* Handle recursion cases */
+	if (kprobe_running()) {
+		p = get_kprobe(addr);
+		if (p) {
+			if (kprobe_status == KPROBE_HIT_SS) {
+				unlock_kprobes();
+				goto no_kprobe;
+			}
+			arch_disarm_kprobe(p);
+			ret = 1;
+		} else {
+			/*
+			 * jprobe instrumented function just completed
+			 */
+			p = current_kprobe;
+			if (p->break_handler && p->break_handler(p, regs)) {
+				goto ss_probe;
+			}
+		}
+	}
+
+	lock_kprobes();
+	p = get_kprobe(addr);
+	if (!p) {
+		unlock_kprobes();
+		goto no_kprobe;
+	}
+
+	kprobe_status = KPROBE_HIT_ACTIVE;
+	current_kprobe = p;
+
+	if (p->pre_handler && p->pre_handler(p, regs))
+		/*
+		 * Our pre-handler is specifically requesting that we just
+		 * do a return.  This is handling the case where the
+		 * pre-handler is really our special jprobe pre-handler.
+		 */
+		return 1;
+
+ss_probe:
+	prepare_ss(p, regs);
+	kprobe_status = KPROBE_HIT_SS;
+	return 1;
+
+no_kprobe:
+	preempt_enable_no_resched();
+	return ret;
+}
+
+static int post_kprobes_handler(struct pt_regs *regs)
+{
+	if (!kprobe_running())
+		return 0;
+
+	if (current_kprobe->post_handler)
+		current_kprobe->post_handler(current_kprobe, regs, 0);
+
+	resume_execution(current_kprobe, regs);
+
+	unlock_kprobes();
+	preempt_enable_no_resched();
+	return 1;
+}
+
+static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	if (!kprobe_running())
+		return 0;
+
+	if (current_kprobe->fault_handler &&
+	    current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+		return 1;
+
+	if (kprobe_status & KPROBE_HIT_SS) {
+		resume_execution(current_kprobe, regs);
+		unlock_kprobes();
+		preempt_enable_no_resched();
+	}
+
+	return 0;
+}
+
+int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
+			     void *data)
+{
+	struct die_args *args = (struct die_args *)data;
+	switch(val) {
+	case DIE_BREAK:
+		if (pre_kprobes_handler(args->regs))
+			return NOTIFY_STOP;
+		break;
+	case DIE_SS:
+		if (post_kprobes_handler(args->regs))
+			return NOTIFY_STOP;
+		break;
+	case DIE_PAGE_FAULT:
+		if (kprobes_fault_handler(args->regs, args->trapnr))
+			return NOTIFY_STOP;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	printk(KERN_WARNING "Jprobes is not supported\n");
+	return 0;
+}
+
+void jprobe_return(void)
+{
+}
+
+int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	return 0;
+}